A thermistor is a resistor with a variable resistance responsive to a change in a surrounding temperature. The rate of change of the variable resistance over the change of temperature defines a temperature coefficient of a thermistor. A thermistor may have a positive or negative temperature coefficient depending on its device physics and mechanical structure. Thermistors have many industrial applications. For instance, thermistors with negative temperature coefficients (NTC) can be used for protecting an electrical component against inrush overvoltage conditions, whereas thermistors with positive temperature coefficient (PTC) can be used for protecting an electrical component against overcurrent conditions.